From 605cdc4346e5f82c031c4a5d6ecd91bf8268f7ff Mon Sep 17 00:00:00 2001
From: Bastien Montagne <bastien@blender.org>
Date: Thu, 11 Nov 2021 14:40:11 +0100
Subject: BKE LibLink/Append: Add mechanism for external code to loop over
 link/append context items.

Will be required for python's `bpy.data.libraries.load()` refactor.
---
 .../blender/blenkernel/BKE_blendfile_link_append.h | 28 +++++++++++++++
 .../blenkernel/intern/blendfile_link_append.c      | 41 ++++++++++++++++++++--
 2 files changed, 66 insertions(+), 3 deletions(-)

(limited to 'source/blender')

diff --git a/source/blender/blenkernel/BKE_blendfile_link_append.h b/source/blender/blenkernel/BKE_blendfile_link_append.h
index 2035f69315c..9e4a498f5e7 100644
--- a/source/blender/blenkernel/BKE_blendfile_link_append.h
+++ b/source/blender/blenkernel/BKE_blendfile_link_append.h
@@ -68,6 +68,34 @@ void *BKE_blendfile_link_append_context_item_userdata_get(
     struct BlendfileLinkAppendContext *lapp_context, struct BlendfileLinkAppendContextItem *item);
 struct ID *BKE_blendfile_link_append_context_item_newid_get(
     struct BlendfileLinkAppendContext *lapp_context, struct BlendfileLinkAppendContextItem *item);
+short BKE_blendfile_link_append_context_item_idcode_get(
+    struct BlendfileLinkAppendContext *lapp_context, struct BlendfileLinkAppendContextItem *item);
+
+typedef enum eBlendfileLinkAppendForeachItemFlag {
+  /** Loop over directly linked items (i.e. those explicitely defined by user code). */
+  BKE_BLENDFILE_LINK_APPEND_FOREACH_ITEM_FLAG_DO_DIRECT = 1 << 0,
+  /** Loop over indirectly linked items (i.e. those defined by internal code, as dependencies of
+   * direct ones).
+   *
+   * IMPORTANT: Those 'indirect' items currently may not cover **all** indrectly linked data. See
+   * comments in #foreach_libblock_link_append_callback. */
+  BKE_BLENDFILE_LINK_APPEND_FOREACH_ITEM_FLAG_DO_INDIRECT = 1 << 0,
+} eBlendfileLinkAppendForeachItemFlag;
+/** Callback called by #BKE_blendfile_link_append_context_item_foreach over each (or a subset of
+ * each) of the items in given #BlendfileLinkAppendContext.
+ *
+ * \param userdata: An opaque void pointer passed to the `callback_function`.
+ *
+ * \return `true` if iteration should continue, `false` otherwise. */
+typedef bool (*BKE_BlendfileLinkAppendContexteItemFunction)(
+    struct BlendfileLinkAppendContext *lapp_context,
+    struct BlendfileLinkAppendContextItem *item,
+    void *userdata);
+void BKE_blendfile_link_append_context_item_foreach(
+    struct BlendfileLinkAppendContext *lapp_context,
+    BKE_BlendfileLinkAppendContexteItemFunction callback_function,
+    const eBlendfileLinkAppendForeachItemFlag flag,
+    void *userdata);
 
 void BKE_blendfile_append(struct BlendfileLinkAppendContext *lapp_context,
                           struct ReportList *reports);
diff --git a/source/blender/blenkernel/intern/blendfile_link_append.c b/source/blender/blenkernel/intern/blendfile_link_append.c
index 107e89e0e1e..36f03990953 100644
--- a/source/blender/blenkernel/intern/blendfile_link_append.c
+++ b/source/blender/blenkernel/intern/blendfile_link_append.c
@@ -277,9 +277,6 @@ void BKE_blendfile_link_append_context_library_add(BlendfileLinkAppendContext *l
   BlendfileLinkAppendContextLibrary *lib_context = BLI_memarena_calloc(lapp_context->memarena,
                                                                        sizeof(*lib_context));
 
-  BlendfileLinkAppendContextLibrary *ctx_lib = BLI_memarena_alloc(lapp_context->memarena,
-                                                                  sizeof(*ctx_lib));
-
   size_t len = strlen(libname) + 1;
   char *libpath = BLI_memarena_alloc(lapp_context->memarena, len);
   BLI_strncpy(libpath, libname, len);
@@ -349,6 +346,44 @@ ID *BKE_blendfile_link_append_context_item_newid_get(
   return item->new_id;
 }
 
+short BKE_blendfile_link_append_context_item_idcode_get(
+    struct BlendfileLinkAppendContext *UNUSED(lapp_context),
+    struct BlendfileLinkAppendContextItem *item)
+{
+  return item->idcode;
+}
+
+/** Iterate over all (or a subset) of the items listed in given #BlendfileLinkAppendContext, and
+ * call the `callback_function` on them.
+ *
+ * \param flag: Control which type of items to process (see
+ * #eBlendfileLinkAppendForeachItemFlag enum flags).
+ * \param userdata: An opaque void pointer passed to the `callback_function`.
+ */
+void BKE_blendfile_link_append_context_item_foreach(
+    struct BlendfileLinkAppendContext *lapp_context,
+    BKE_BlendfileLinkAppendContexteItemFunction callback_function,
+    const eBlendfileLinkAppendForeachItemFlag flag,
+    void *userdata)
+{
+  for (LinkNode *itemlink = lapp_context->items.list; itemlink; itemlink = itemlink->next) {
+    BlendfileLinkAppendContextItem *item = itemlink->link;
+
+    if ((flag & BKE_BLENDFILE_LINK_APPEND_FOREACH_ITEM_FLAG_DO_DIRECT) == 0 &&
+        (item->tag & LINK_APPEND_TAG_INDIRECT) == 0) {
+      continue;
+    }
+    if ((flag & BKE_BLENDFILE_LINK_APPEND_FOREACH_ITEM_FLAG_DO_INDIRECT) == 0 &&
+        (item->tag & LINK_APPEND_TAG_INDIRECT) != 0) {
+      continue;
+    }
+
+    if (!callback_function(lapp_context, item, userdata)) {
+      break;
+    }
+  }
+}
+
 /** \} */
 
 /* -------------------------------------------------------------------- */
-- 
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